Patent GB-832013-A (GB)
Title: Improvements in or relating to automatic work controls for machines
Inventor: MYSKA GUNTER
IPC: D05B35/12
Filed: 1956-09-11
Abstract: 832,013. Sewing machines. PFAFF A. G., G. M. Sept. 11, 1956, No. 27702/56. Class 112 Buttonhole machines, feed by clamp. A sewing machine adapted to perform successive stitching operations and having an automatic stop acting at the end of an operation comprises a carriage supporting a workpiece, an electrically operated control device to drive the carriage so as to advance the latter from each operating point to the next between successive operations, the operating points being separated by predetermined spaces which are not necessarily equal, starting means for initiating an operation each time the carriage has reached an operating point, and means associated with said automatic stop for initiating the next advance of the carriage after each operation except the last is concluded. As described, a buttonhole sewing machine 1 is provided with a carriage 9 in which the work is clamped and whch is automatically driven from one stitching position to another by means of an electrically operated control device 11. Arms 24, 27 are pivotally mounted, by means of pins 35, in brackets 36, 37. A shaft 23, journalled in arm 24, has slidably mounted at its free end a gear pinion 17, and shaft 26 similarly carries a roller 21. Shaft 23 is driven from the control means 11 via an intermediate shaft 18 and universal joints 19, 20, joint 19 being coupled to shaft 18 by means of a shaft 136 telescoping into the latter. Pinion 17 is adapted to mesh with a rack 14 against which roller 21 also bears. Shafts 23, 26 pass through slots 101, 102 in the respective limbs 99, 100 of a channel member secured to rack 14. A pressure plate 96, adapted to bear on the upper surface of the work, is also fixed to rack 14. A bar 12 carries a pressure plate 97 adapted to bear on the lower surface of the work, and plate 97 carries a forwardly-extending work-supporting plate 109. Arms 93, extending rearwardly from plate 96, are pivotally connected to arms 92 extending rearwardly from plate 97, by means of pin-and-slot connections 94, 95. Rollers 40, 41 carried by shafts 42, 43, journalled in brackets 44, 45, bear against plate 97 in opposition to pinion 17 and roller 21. Sleeves 46, 47 carried in extensions of shafts 42, 43 pass through slots 48, 49 in plates 50, 51 depending from plate 109. Rearward extensions 28, 29 of arms 24, 27 are connected by rods 30, 31 and levers 33, 34 to a pedal 32. Operation of the latter serves to raise arms 24, 27 and plate 96 against the bias of spring 25, when pinion 17 is disengaged from rack 14 by means of springs 105 acting on bars 107 interconnecting plates 103, 104 formed with slots through which the shafts 23, 26 pass. Rods 76, pivoted at 77 to extensions 28, 29 are slidable in the ends of rods 71, 72 which are adjustably coupled to rods 67, 68, the latter being connected by ball- and-socket joints 59, 60 to rods 55, 56 slidably mounted in sleeves 57, 58. Brackets 36, 44 and sleeve 57 are carried by a plate 65 slidable in a support 78, and brackets 37, 45 and sleeve 58 are carried by a plate 66 slidable in a support 79, said supports being spaced from table top 85 by members 80 and carrying depending rods 81 secured to the table top. A profiled plate 15 fixed to bar 12, bears rearwardly against rollers 16 carried by the sleeves 57, 58, and forwardly against further rollers 16 carried by the rods 55, 56, the latter rollers being biased against plate 15 by means of springs 62 acting on the rods 55, 56. Operation of pedal 32 to raise arms 24, 27 thereby also serves to move the forward rollers 16 away from plate 15, whereby to facilitate the removal of the work clamping and feeding carriage 9, comprising the plates 96, 97, from the machine. Plate 50 carries a rack 113 engaged by a spring-biased pawl 114 mounted on an arm 117 fixed to plate 65. A cam 119, carried by an arm 120 fixed to rod 55, is adapted to trip pawl 114 when pedal 32 is operated, whereby the carriage is returned to its initial position by means of a cable 134 wound on a spring-biased drum 133 fixed to support 79. The free end of arm 120 carries a pair of switches 121, 122 adapted to be closed by any one of a series of pairs of actuators 123, 124 slidably mounted on a bar 125 carried by plate 51, and securable thereon by screws 126. Pointers 127 carried by said pairs of actuators co-operate with a scale 128 fixed to a member 129 which is also slidable on bar 125 and is securable thereon by means of a screw 126. A pointer 131 on member 129 co-operates with a mark 132 carried by the switches 121, 122. A link 87 has a bifurcated front end connected by pivot pins 89 to the pivot pins 35, and a rear end 90 connected at 91 to the operating lever 3 of the work clamp 4 of the buttonhole machine, whereby the carriage 9 moves in unison with the clamp 4. To increase the pressure on the workpiece, electromagnets 98 are mounted on the upper pressure plate 98 which consists of a non- magnetic material. A foot switch 262, incorporated in the treadle 32, serves to disconnect the electromagnets when the treadle is depressed for raising the upper jaw of the carriage. In the position of non-use a rotary switch 179, operable only in the direction of the arrow 180, is open, a switch 141 is closed, and the contact arms 232, 245 of rotary stepping switches 142, 144 are in the "on" and "off" positions respectively. On closing switch 179 a solenoid 228, associated with switch 142, is energized to attract an arm 234, whereby arm 232 is moved to the "off" position. Treadle 32 is then depressed for the insertion of the workpiece. On release of the treadle, the machine is started by pressing a button 137 to close a switch 175, whereby a solenoid 176 is energized to operate a machine-starting treadle 2 via a flexible cable 177. When the machine starts, switch 141 is opened by an arm 140 associated with the starting lever 139, and, when the machine stops automatically on completion of the buttonhole, switch 141 closes to energize solenoid 228, whereby arm 232 is moved to the "on" position and a motor 143 is thereby started for driving shaft 18 via gears 155 and 154. Shaft 18 continues to rotate for advancing carriage 9, the latter being also displaced at right angles to the advance movement by the co-operation of the profiled plate 15 with the guide rollers 16, until the switches 121, 122 are closed by the first pair of actuators 123, 124, actuator 124 closing and releasing switch 122 before actuator 123 engages switch 121. A solenoid 237, associated with switch 142, is then energized via switch 121, whereby arm 232 is moved to the "off" position to stop the motor 143. A solenoid 240, associated with switch 144, is energized via switch 122, whereby arm 245 is moved to the "on" position to start a motor 182. The latter drives the shaft 185 of a pulse-generator 145, whereby a contact arm 246 is moved over one of a series of contacts 188 to energize the starting solenoid 176, and a cam 186 closes a switch 187 to energize solenoid 240 for moving arm 245 to the "off" position to stop motor 182. When rack 14 is moved on completion of the last buttonhole, a single final actuator 178 serves to close switch 121 for stopping motor 143, and when switch 179 is finally turned to the "off" position it momentarily closes a contact 181 to energize solenoid 237 and thereby move arm 232 to the "on" position. In a modification, the actuator for switches 121, 122 are carried by a disc which is driven, by gearing, from shaft 18. The pulse-generator 145 may be replaced by a delayed-action relay, controlled by switch 122 and adapted to close a contact in the circuit of the starting solenoid 176. The motor 143 may be replaced by a magnetic clutch coupling driven from a continuously rotating part of the machine, the clutch being controlled by the switch 142. In a further modification, Fig. 4, shaft 18 is driven by a rack 158 which co-operates with a pinion 254 to drive a shaft 255, which is coupled with shaft 18 to drive the latter unidirectionally through ratchet-and pawl means 256, 257, 258. Rack 158 is suspended from one end of a lever 157, the other end of which is connected by a link 156 to the gear 154 driven by the motor 143, one revolution of gear 154 corresponding to the movement of the carriage from one sewing position to the next. The fulcrum 253 of lever 157 is mounted on a member 159 adapted to be displaced by screw means 251, 252 for varying the stroke of rack 158, the extent of said stroke being indicated by a pointer carried by member 159 and moving over a scale 160. A shaft 151, driven by gear 154, carries a pair of actuators 152, 153 adapted to close the switches 122, 121 once per revolution of shaft 151. A preselector 161 comprises a shaft 171 carrying a knob 174 having a pointer movable over a scale 173 to preselect the number of buttonholing operations. Cams 172 on shaft 171 are adapted to close switches 162 to 170 connected to the respective contacts 188 of the pulse generator 145. A switch 214 enables starting solenoids 215, 216 of additional machines to be connected in parallel with solenoid 176, the carriages of said machines being driven by respective gears 218, 219 meshing with a gear 217 on shaft 18. Auxiliary switches 200 to 203 of the pre-selector may be connected to a second ring of contacts in the pulse generator 145, the circuits so formed, by shunting the switch 187, being adapted to return the arm 246 to its initial position automatically. Auxiliary switches 207 to 212 may be connected to a third ring of contacts, the circuits being arranged to control a solenoid adapted to prevent operation of the starting switch 175 during a programme of machine operation.